How would you react to a wide-spread Mac OS X virus?

One of the long-standing major appeals of the Mac OS has been its relatively small and low-impact ratio of serious security vulnerabilities and virus attacks. Users wear it like a badge on their shoulder, and even Apple has jumped in by flat-out bragging about Mac OS X's security with their latest Get a Mac ad campaign.

While the debate surrounding exactly why the Mac has earned this reputation has raged at least since the term 'trolling' was coined, I'm a bit more interested in bending the space-time continuum and asking you, dear readers, a hypothetical: what would happen if a truly malicious Mac OS X virus were to break out in large scale? I'm talking about something along the lines of the Sasser worm, which grounded some Delta Airline flights, brought many other companies to their knees, and is estimated to have caused billions in damage.

I know Apple's machines aren't quite as integral to the various operations of our society and businesses like Windows and Linux are, but it would be hard to argue that a good portion of of the Mac user base doesn't care about the security of their chosen OS. With this in mind, I wonder: would you keep your Mac in a day and age when 3rd party virus and security tools become a basic necessity of Mac OS X? Would you bite the bullet and buy Norton Virus Mega Security Bundle Premium 2007 beta 5? Do you think all those switchers - reeled in by Apple's "We don't have any viruses" Get a Mac commercials - would become crippled in disillusion?

What say you, TUAW readers. How large of a hole in Apple's security record would be 'too large'?